A. Field of the Invention
This invention relates to computer simulation systems and, in particular, to a computer system for simulating a user-specified automated manufacturing and/or materials handling facility.
B. Prior State of the Art, and Principal Objects of the Invention
Over the last decade digital computers, including minicomputers and microprocessors, have increasingly been used to automate materials handling and manufacturing facilities. Particularly in large scale operations, automation of manufacturing and warehousing facilities may result in significant savings due to increased efficiency and fewer errors. However, automated manufacturing and/or materials handling (AM/MH) facilities are expensive to properly design, install and make operational.
The high costs which are associated in acquiring and installing automated equipment such as storage/retrieval (S/R) machines, automatic guided vehicles (AGVs), automated conveyor systems, and automated machining centers underscores the importance of properly designing the overall system at the outset. Obviously, it is extremely disadvantageous and expensive to install sophisticated automated machines and equipment only to later find out that the equipment is not able to properly function in the system and does not integrate properly with the other computer-controlled components of the facility.
In the past, design, installation and testing of automated manufacturing and materials handling facilities has been approached in basically one of two ways. One way is to simply install the system after it is designed, and then to manually debug the system by trial and error. This procedure is both time consuming and inefficient. It requires that the valuable time of skilled operators as well as the time of the computer-controlled components be used to "walk through" the system operation under various operating conditions in order to correct any conflicts in the routing, performance or operation of the components.
For example, it may happen that two or more wire-guided vehicles of the facility are not properly programmed and may reach an intersection in their routing at the same time. These types of errors must of course be corrected in order for the automated manufacturing or materials handling facility to operate properly. In the worst case, it may happen that the particular components selected for the system simply are not capable of functioning properly in the overall system design. For example, a wire-guided vehicle system may not be able to properly service all of the loads which are supplied to it by an automated conveyor system. In that case, expensive and costly design changes must be made to the system after installation.
The other basic approach which has been used to accomplish design and installation of automated manufacturing and materials handling facilities involves the development and testing of computer simulated models of the system using GPSS or other general purpose simulation languages. This approach has the important advantage that before making the final investment to purchase and install the complex and expensive computer-controlled components which make up a particular design for an automated manufacturing or materials handling facility, the user can test the operation of the model to determine whether it will perform as expected in response to given parameters or conditions simulating those of the actual facility.
Once developed, the model can be used to evaluate alternative designs in order to optimize the final design and operation of the facility. For many types of automated manufacturing or materials handling facilities, this type of computer simulation has been the most efficient and accurate way of developing a system design. For facilities which are extremely complex, computer simulation is perhaps the only practical approach to solving the design problem.
The disadvantage to computer simulation of automated manufacturing or materials handling facilities is that the problem of developing the simulation model is itself so complicated and difficult that historically it requires the use of someone who has been specially trained in the use of general purpose simulation languages and programming techniques based on such languages. However, generally such experts are not experienced in solving particular design problems in the art of automated manufacturing or materials handling. Thus, it is not uncommon for these types of experts to spend substantial time and effort working with automated manufacturing and materials handling designers in order to understand the basic parameters which they will need to use in order to develop a simulation model of such a facility. This of course increases the time, risk and expense involved in developing such models, and is a serious drawback.
In view of the aforementioned problems and prior state of the art, it is a primary object of the present invention to provide a computer system which can be easily used by designers of automated manufacturing or materials handling facilities to efficiently and inexpensively generate simulation models of such facilities without having to rely upon the assistance of experts who are specially trained in computer simulation and programming techniques based on general simulation languages.
Another principal object of this invention is to provide a computer system for simulating a user-specified automated manufacturing and/or materials handling facility which easily and accurately predicts the response of the facility to certain operating parameters and conditions so as to permit alternate designs to be evaluated in order to optimize facility design.
Yet another principal object of the present invention is to provide a computer system for simulating a user-specified automated manufacturing and/or materials handling facility which is significantly less expensive, more accurate and more efficient to use than present state-of-the-art general or special purpose simulation systems.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.